OB Global Package

I have a group of 5 OB-GYN. If they provide the entire package including the delivery can they bill for subsequent visits while patient is in hospital after delivery? Example: Doctor 1 delivers, however next day doctor 2 is on call and does the subsequent visit can doctor 2 bill subsequent visit using delivery diag? I have had BCBS pay this as I tried it once to see if they would pay and yes they did. But before I do this again I want to make sure it is allowed. They are all on the same tax id but as I said they did pay this as long as it is not the same doctor who delivers. Is it possible that some insurances allow this and others don't as with OB visits that exceed the global package?